The objective of this proposed research is to develop an in vitro model for the study of the factors involved in the differentiation of odontoblasts during wound healing in the dental pulp. Most of our knowledge in this area is descriptive in nature; we know virtually nothing about the fundamental biology of the early stages of pulp repair. In vivo investigation has been hampered by a scarcity of tissue for biochemical and immunologic studies and a hard tissue encasement which complicates immunohistochemistry. As a result, most studies on wound healing in huma and animal teeth have been histologic evaluations of wound dressings such as calcium hydroxide. In order to rationally approach pulp treatment in the future, more knowledge about pulp healing is crucial. Two culture systems will be investigated as possible models for studying pulp wound repair. Both involve the use of defined media and the treatment of pulp tissues with staged wound fluid or cells harvested from wire mesh cylinders implanted in rats. The first model will involve the cultivation of mature rat pulp on a millipore filter system. Wound cells fluid, or both will be placed transfilter, with the expectation that odontoblast differentiation will be observed histologically. In the second, fetal rat tooth germs will be placed onto filters in an inverted position. The incomplete cervical areas facing upward will then be covered by wound fluid cells, or both. In the manner of tooth germs transplanted in vivo, the cervix is expected to form a barrier of fibrodentin and dentin. Since both culture systems will utilize defined media distinguishing the role of wound factors in promoting odontoblast differentiation individually or in combination will facilitated.